The 19' Scamp is a 5th wheel I'd seen previously, although never on a RL (G1 or G2). The 2200-2800 lbs listed is dry weight; the Scamp people say loaded somewhere in the 3500 lb range, with a pin/tongue weight of 400-500 lbs. Those are easily within the capacity of a RL and still leave a bit of margin for gear or passengers in the truck.
However...it turns out the Scamp folks also say their 5th wheel specifically doesn't work with three small trucks...Honda Ridgeline, Chevy Avalanche, and the Ford model (don't recall the name). They say the RL doesn't work because of the trunk, although I suspect it may be something else since the hitch will be in front of the trunk, closer to the axle.
Alas, there are other Scamps--and many other brands of ultra-lite trailers--the RL can handle on the regular trailer hitch; it just seems 500 lbs tongue weight back there is harder on the truck than even 6 or 700 lbs over the rear axle.